Please cite this article as: Stocchi, A., Colabella, L., Cisilino, A., Álvarez, V., Manufacturing and Testing of a Sandwich panel honeycomb core reinforced with natural-fiber fabrics, Materials and Design (2013), doi: http:// dx.doi.org/10.1016/j.matdes. 2013.09.054 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The large wall thickness relative to the cell size of the jute-vinylester cores, which inhibits buckling, and the heterogeneities in the composite, which are preferential damage initiation sites, explain the observed behavior. When compared in terms of the specific strengths, the jute/vinylester cores introduced in this work show similar performances to those of their commercially available counterparts. The results from this study suggest that jute-reinforced cores have the potential to be an alternative to standard cores in applications that sustain compressive static loads.

A multi-scale analysis of the linear elastic and the early damage stages of ferritic ductile iron is introduced in this work. The methodology combines numerical and experimental analyses in the macro and micro scales. Experiments in the micro-sea le are used for the characterization of the material micro constituents and the assessment of the micro-sea le damage mechanisms; experiments in the macro-sea le provide the data to calibrate and validate the models. The 20 multi-scale problem is modeled using the pre-critica! regime of the Failure-Oriented Multi-Scale Variational Formulation (FOMF), which is implemented via a FE 2 approach. Finite element analysis in the micro-sea le is customized to account for plastic deformation and matrix-nodule debonding. The multi-scale model is found effective for capturing the sequence and extent of the damage mechanisms in the micro-scale and to estímate, via inverse analyses, parameters ofthe matrix-nodule debonding law. Results allow to develop new insights for the better understanding of the ductile iron damage mechanics and to draw conclusions related to the modeling aspects of the multi-scale simulation.

Purpose -The purpose of this paper is to further develop the truss-like discrete element method (DEM) in order to make it suitable to deal with damage and fracture problems. Design/methodology/approach -Finite and boundary elements are the best developed methods in the field of numerical fracture and damage mechanics. However, these methods are based on a continuum approach, and thus, the modelling of crack nucleation and propagation could be sometimes a cumbersome task. Besides, discrete methods possess the natural ability to introduce discontinuities in a very direct and intuitive way by simply breaking the link between their discrete components. Within this context, the present work extends the capabilities of a truss-like DEM via the introduction of three novel features: a tri-linear elasto-plastic constitutive law; a methodology for crack discretization and the computation of stress intensity factors; and a methodology for the computation of the stress field components from the unixial discrete-element results. Findings -Obtained results show the suitability and the performance of the proposed methodologies to solve static and dynamic crack problems (including crack propagation) in brittle and elasto-plastic materials. Computed results are in good agreement with experimental and numerical results reported in the bibliography. Research limitations/implications -This paper demonstrates the versatility of the truss-like DEM to deal with damage mechanics problems. The approach used in this work can be extended to the implementation of time-dependent damage mechanisms. Besides, the capabilities of the discrete approach could be exploited by coupling the truss-like DEM to finite and boundary element methods. Coupling strategies would allow using the DEM to model the regions of the problem where crack nucleation and propagation occurs, while finite or boundary elements are used to model the undamaged regions. Originality/value -The scope of the truss-like DEM has been extended. New procedures have been introduced to deal with elastoplastic-crack problems and to improve the post processing of the stress results. IntroductionDuring the 1960s an alternative set of computational methods that do not use a set of differential or integral equations to describe the problem were introduced. Depending on the individual element introduced, such as particles, agents or molecules, methods such as molecular dynamics, discrete element method (DEM), discontinuous deformation analysis, and similar were invented. In the process, computational mechanics of discontinua emerged, and its is now an integral part of cutting edge research in nanotechnology and industrial processes spanning over diverse fields as mining, milling, pharmaceuticals, powders, ceramics, composites, blasting, construction, etc. (Munjiza, 2009).The numerical simulation of fracture and damage problems is always an active research topic. Finite and boundary element methods (BEMs) are the best developed methods in this field (Anderson, 2005;Aliabadi and Rooke, 1991...